Physicists working at the Brookhaven National Lab's Relativistic Heavy Ion Collider (RHIC) are exploring the puzzle of proton spin as they begin taking data during the 2009 RHIC run. For the first time, RHIC is running at a record energy of 500 giga-electron volts (GeV) per collision, more than double the previous runs in which polarized proton beams collided at 200 GeV. Narrarated by RHIC run coordinator Mei Bai.